Electromagnet.



W. M. DAVIS.

ELEOTROMAGNET.

APPLICATION FILED vAPR. 26, 1901.

PATENTED SEPT. l, 1903.

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m: norms runs co, woYo-uma, wumncwon n UNITED STATES iatented September1, 1901;.

PATENT OFFICE.

WILLIAM M. DAVIS, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGN-MENTS, TO STROMBERG-CARLSON TELEPHONE MANUFACTURING COM- PANY, OFROCHESTER, NEW YORK, A CORPORATION OF NEW YORK.

ELECTROMAGNET.

SPECIFICATION forming part of Letters Patent No. 737,589, datedSeptember 1, 1903.

Application filed April 26, 1901.

T aZZ whom it may concern.-

Be it known that I, WILLIAM M. DAVIS, a citizen of the United States,residing at Chicago, in the county of Cook and State of Illinois, haveinvented a certain new and useful Improvement in Electromagnets, ofwhich the following is a full, clear, concise, and exact description,reference being had to the accompanying drawin gs,formin g a part ofthis speci- I0 fication.

My invention relates to relays or operating electromagnets employingmovable armatures.

The invention has for one of its objects the I 5 provision of meanswhereby the magnetic circuit may include the most limited airgap,whereby the efficiency and power of the electromagnet is increased.

The invention has for its further object the construction of anelectromagnet employed for the purpose of effecting circuit changeswherein a positive thrust of the circuit-changing switch may be securedin a desired direction.

In practicing my invention I prefer to provide the core of theelectromagnet with extensions of magnetic material, with one of whichthe armature has pivotal or swinging connection, this armature beingnormally removed from the other extension a short space, this spacebeing preferably the only gap in the magnetic circuit. The free end ofthe armature is preferably maintained in its normal position by means ofa spring that acts as the 3 5 circuit-changing switch, the helix of theelectromagnet being preferably interposed between the armature and thesaid spring,whi1e the connection between the armature and spring issecured bymeans of a distance-piece,

preferably in the form of a rod of insulating material.

I will explain my invention more 'fully by reference to the accompanyingdrawings, showing the preferred embodiment thereof,

in Which Figure 1 illustrates a subscribcrs station united with thetelephone-exchange; Fig. 2, a sectional elevation of the electromagnetof my invention; Fig. 3, a plan view thereof;

Serial No. 57,594. (No model.)

Fig. 4, the detail of a circuit-changing spring; Fig. 5, the detail ofthe hinge connection of the armature on line 5 5 of Fig. 3; Fig. 6, asectional view on line 6 6 of Fig. 5.

Like parts are indicated by similar characters of reference throughoutthe different fig- 5 5 ures.

I have illustrated the electromagnet of my invention as employed inconnection with a telephoneexchange system; but I do not wish to belimited to this construction.

The telephone system illustrated in Fig. 1 is a common battery system.At the substation I have illustrated that type of apparatus which isadapted for use in connection with common battery systems wherein thetransmitter a is included in series with the main lines I; l) and theprimary coil 0. A telephone-switch hook d is employed for cutting theprimary coil and the transmitter into circuit with the main line whenthe receiver c is removed from its hook and to cut this transmitter andprimary coil out of circuit when the receiver is replaced upon its hook,in which position the signal-bellf is cut into circuit.

I have illustrated the lines I) b as being connected with theline-springs of a springjack g and have illustrated one plug h, havingin this instance its sleeve connected with one terminal of the commonbattery through the impedance-coil 1'. I have not deemed it essential toillustrate the telephonic apparatus in detail, as it is sufficientlywellknown to those skilled in the art.

The relay 7.: is in this instance provided with a differential Windingthat normally inc'ludes a battery Z and a line-indicator m and also acircuit-changin g spring at, which in its normal position rests againstan upper contact 0, that constitutes a terminal of the difo ferentialWinding. WVhen the relay is inthe normal position illustrated, circuitthrough the battery Z and indicator on may be completed by the removalof the receiver a from its telephone-switch hook, the switch thereuponserving to close this circuit. As the windings are differential andequal in magnetizing effect, the relay will not be energizedsufficiently to actuate the switch at, so that the indicator m may beoperated by the subscriber. WVhen the operator inserts the plug h intothis subscribers jack, the coil 7; of the differential winding mayreceive more current than the companion coil k whereupon the magnetizingeffects of the differential coils are unbalanced, so that the relays maybe energized sufficiently to effect an actuation of the switch at toopen contact through the coil 70 and thereby cut the line-indicator onout of service during the insertion of the plug h within said jack.

The relay or electromagnet of my invention preferably comprises acentrally disposed core 1), having angular extensions 1) p at its ends,said core and extensions being of magnetizable material, preferablysoftiron. These extensions pp preferably project first at right angles tothe core and then at their upper ends a slight distance paralleltherewith, the portions of the extensions that are parallel with thecore preferably projecting toward each other. The extension 13 ispreferably provided with a projection 19 preferably formed integrallytherewith, which projection constitutes a fulcrum or pivotal point forthe armature q, that is provided with a corresponding recess thatengages the projection p whereby the armature is afforded a pivotalconnection that has intimate contact with the extension 19, so that themagnetic circuit includin g the armature is not impaired by reason ofthe connection. The armature extends longitudinally of the core andhelix of the magnet and is normally maintained in a separated relationwith the extension 19 by means of the circuit-changing switch n. Thiscircuit-changing switch is placed upon the opposite side of theelectromagnet, and connection is afforded between the same and thearmature by means of the insulating-rod '1, that is preferably rigidlysecured to the free end of the armature by means of a screw 3 and isadapted for sliding engagement with the circuit-changing spring byhaving its threaded extension t movable in the slot 10. To maintain thearmature in its pivotal engagement with the extension 19, I employ aspring 1), which is preferably in the form of a leaf-spring, secured tothe corresponding end of the core and bent at right angles at its upperportion to engage the ridge formed in the armature where the projection13 is engaged therewith.

\Vhile I have herein shown and particularly described the preferredembodiment of my invention, I do not wish to be limited to the preciseconstruction herein set forth; but,

Having thus described my invention, I claim as new and desire to secureby Letters Patent- 1. In an electromagnetic circuit-changing device, thecombination with an electromagnet-core, of an extension on either end ofsaid core, an armature pivotally associated with one of said extensionsand substantially parallel to said core, a circuit-changing springsubstantially parallel to said armature, the electromagnet-winding beinginterposed between the armature and said spring, and a mechanicalconnection intervening between and engaging the free end of saidarmature and of said spring, substantially as described.

2. In an electromagnetic circuit-changing device, the combination withan electromagnet, of a pivoted armature, a circuit-changing spring, theelectromagnet-winding being interposed between the armature and saidspring, and a mechanical connection intervening between the free end ofsaid armature and the said spring, the said mechanical connection havingfixed engagement with the armature and a sliding engagement with thespring, substantially as described.

3; In an electromagnetic circuit-changing device, the combination withan electromagnet-core, of an extension on said core, and an armaturepivotally connected with said extension by an enlargement upon saidextension engaging a depression in said armature, substantially asdescribed.

4. In an electromagnetic circuit-changing device, the combination withan electromagnet-core, of an extension on said core, an armaturepivotally connected with said extension by an enlargement upon saidextension engaging a depression in said armature, and a spring adaptedto maintain said armature in pivotal connection with said extension,substantially as described 5. In an electromagnetic circuit-changingdevice, the combination with an electromagnet, of an armature pivotallyconnected with the core of said electromagnet by an enlargement on saidcore engaging a corresponding depression in said armature, a springadapted to maintain said armature in en gagement with saidelectromagnet-core, a circuit-changing spring, the electromagnet-windingbeing interposed between the armature and said circuit-changing spring,and a mechanical connection intervening between the free end of saidarmature and said circuit changing spring, substantially as described.

6. In an electromagnetic circuit-changing device, the combination withan electromagnet-core, of extensions on either end of said core, anarmature pivotally connected with one of said extensions by anenlargement on said extension engaging a corresponding depression insaid armature, a winding on said core, a circuit-changing spring, theelectromagnet-windin g bein g interposed between the armature and saidcircuit-changing spring, and a mechanical connection intervening betweenthe free end of said armature and said circuit-changing spring,substantially as described.

7. In an electromagnetic circuit-changing device, the combination withan electromagnet-core, of extensions on either end of said core, anarmature pivotally connected with one of said extensions by anenlargement on said extension engaging a corresponding depression insaid armature, a Winding on said core, a spring adapted to maintain thepivotal association of said armature with said extension, acircuit-changing spring, the electromagnet-winding being interposedbetween the armature and said circuit changing spring, and a mechanicalconnection intervening between the free end of said armature and saidcircuit-changing spring, substan- 1o tiaily as described.

In Witness whereof I hereunto subscribe my name this 20th day of April,A. D. 1901.

\VILLIAM M. DAVIS.

Witnesses GEORGE L. CRAGG, MAX W. ZA'BEL.

